Lindsay Lohan’s already landed the next role in her acting comeback: starring in an upcoming Lady Gaga music video off the singer’s anticipated album, “ARTPOP,” sources say.

Gaga and Lohan have become fast friends and made headlines by hanging out at the Chateau Marmont last month. Gaga posted pics of their encounter — she in a tiara and pearls while Lohan covered her mouth with a French-manicured hand — on her Web site Little Monsters. But, it seems, the collaboration is going a step further.

“Lady Gaga and Lindsay caused a stir last month when they had their ‘sleepover’ at the Chateau [Marmont],” a Hollywood insider told us, adding, “and now it turns out that Lindsay will be starring in Gaga’s new video from her upcoming album.”

But the potential Gaga gig represents a more mainstream opportunity. “Due to Gaga’s superstar status, this would be Lindsay’s biggest [role] by far in many, many years,” a source said.

But others wonder why Gaga’s involving Lohan. “Why this huge artist — who could literally have anyone she wants — chose someone currently at the bottom of the Hollywood food chain remains a mystery,” one observer sniffed.

Gaga recently wrapped an acting role herself in Robert Rodriguez’s “Machete Kills” with Sofia Vergara, Jessica Alba, Amber Heard, Charlie Sheen and Mel Gibson. And she’s just starting to let details of “ARTPOP” — which has no release date — trickle. She tweeted the title over the weekend, and teased fans last month by blasting a new song on the streets of New York.

Gaga was spotted Monday having lunch with her family at Philippe. She’d visited hush-hush beau Taylor Kinney in Chicago over the weekend during Lollapalooza, as we reported.

A source close to Gaga said, “Lady Gaga’s not shooting a music video at this time.” Reps for Gaga and LiLo declined comment.